Shape-memory polymers (SMPs) form a class of materials that can store and release elastic energy upon applying an external stimulus, such as heat or light. A shape-memory material can be deformed to a temporary shape and can return to its original shape after the application of an external stimulus, such as temperature. For example, a material heated above its shape-memory transition temperature, TSM, can be elastically deformed by subjecting it to external stresses and subsequently cooled, while under stress, beneath TSM. In the cooled state, external stresses can be removed and the material can retain its deformed shape. Upon heating above TSM, the material can recover its elastic strain energy and can return to its original shape. SMPs are noted for their ability to recover from large strains—up to several hundred percent—which can be imposed by mechanical loading. The large-strain recovery Observed in SMPs is a manifestation of entropy elasticity.
SMPs can serve in biomedical devices such as vascular stents, clot-removal devices, catheters, programmable sutures, implants, and numerous other applications. Applications increasingly demand that shape-memory materials perform mechanical work against external loads; therefore, SMPs, in certain circumstances, should be able to store large amounts of elastic energy per unit volume, or equivalently should exhibit high shape energy densities, which are seldom measured (Anthamatten, M et al. Macromolecules 2013, 46(10), 4230-4234). Other commercialization requirements are diverse but may include: (i) a specified shape recovery stimulus (heat, light, chemical)—for thermal stimulus, a tunable shape recovery temperature, TSM, near the body's temperature is often needed; (ii) ease of processability into different shapes; (iii) reproducible and robust shape-memory behavior upon cycling; (iv) and low cost and straightforward scale-up. What are thus needed are new SMP's and methods of making and using them. The methods and compositions disclosed herein address these and other needs.